RESUMO
Brook charr is a cold-water species which is highly sensitive to increased water temperatures, such as those associated with climate change. Environmental variation can potentially induce phenotypic changes that are inherited across generations, for instance, via epigenetic mechanisms. Here, we tested whether parental thermal regimes (intergenerational plasticity) and offspring-rearing temperatures (within-generational plasticity) modify the brain transcriptome of Brook charr progeny (fry stage). Parents were exposed to either cold or warm temperatures during final gonad maturation and their progeny were reared at 5 or 8 °C during the first stages of development. Illumina Novaseq6000 was used to sequence the brain transcriptome at the yolk sac resorption stage. The number of differentially expressed genes was very low when comparing fry reared at different temperatures (79 differentially expressed genes). In contrast, 9,050 differentially expressed genes were significantly differentially expressed between fry issued from parents exposed to either cold or warm temperatures. There was a significant downregulation of processes related to neural and synaptic activity in fry originating from the warm parental group vs fry from the cold parental one. We also observed significant upregulation of DNA methylation genes and of the most salient processes associated with compensation to warming, such as metabolism, cellular response to stress, and adaptive immunity.
Assuntos
Metilação de DNA , Fenótipo , Transcriptoma , Truta , Animais , Truta/genética , Temperatura , Perfilação da Expressão Gênica , Feminino , Masculino , Encéfalo/metabolismo , Epigênese GenéticaRESUMO
While Atlantic salmon (Salmo salar) of the northernmost American populations is alimentary, economically, and culturally important for Ungava Inuit communities (Nunavik, Canada) and might play a key role in the persistence of the species in a global warming context, many mysteries remain about those remote and atypical populations. Thus, our first aim was to document the genomic structure of the Nunavik populations. The second objective was to determine whether salmon only migrating to the estuary without reaching the sea, apparently unique to those populations, represent distinct populations from the typical anadromous salmons and subsequently explore the genetic basis of migratory life-history tactics in the species. Finally, the third goal was to quantify the contribution of each genetically distinct population and life-history tactic in the mixed-stock subsistence fishery of the Koksoak R. estuary. We used Genotyping-by-Sequencing to genotype 14,061 single nucleotide polymorphisms in the genome of 248 individuals from 8 source populations and 280 individuals from the Koksoak estuary mixed-stock fishery. Life-history tactics were identified by a visual assessment of scales. Results show a hierarchical structure mainly influenced by isolation-by-distance with 7 populations out of the 8 studied rivers. While no obvious structure was detected between marine and estuarine salmon within the population, we have identified genomic regions putatively associated with those migration tactics. Finally, all salmon captured in the Koksoak estuary originated from the Koksoak drainage and mostly from 2 tributaries, but no inter-annual variation in the contribution of these tributaries was found. Our results indicate, however, that both marine and estuarine salmon contribute substantially to estuarine fisheries and that there is inter-annual variation in this contribution. These findings provide crucial information for the conservation of salmon populations in a rapidly changing ecosystem, as well as for fishery management to improve the food security of Inuit communities.
RESUMO
Plasmodiophora brassicae (Woronin, 1877), a biotrophic, obligate parasite, is the causal agent of clubroot disease in brassicas. The clubroot pathogen has been reported in more than 80 countries worldwide, causing economic losses of hundreds of millions every year. Despite its widespread impact, very little is known about the molecular strategies it employs to induce the characteristic clubs in the roots of susceptible hosts during infection, nor about the mechanisms it uses to overcome genetic resistance. Here, we provide the first telomere-to-telomere complete genome of P. brassicae. We generated â¼27 Gb of Illumina, Oxford Nanopore, and PacBio HiFi data from resting spores of strain Pb3A and produced a 25.3 Mb assembly comprising 20 chromosomes, with an N50 of 1.37 Mb. The BUSCO score, the highest reported for any member of the group Rhizaria (Eukaryota: 88.2%), highlights the limitations within the Eukaryota database for members of this lineage. Using available transcriptomic data and protein evidence, we annotated the Pb3A genome, identifying 10,521 protein-coding gene models. This high-quality, complete genome of P. brassicae will serve as a crucial resource for the plant pathology community to advance the much-needed understanding of the evolution of the clubroot pathogen.
Assuntos
Plasmodioforídeos , Telômero , Plasmodioforídeos/genética , Telômero/genética , Doenças das Plantas/parasitologia , Genoma de ProtozoárioRESUMO
The primary focus of medicinal cannabis research is to ensure the stability of cannabis lines for consistent administration of chemically uniform products to patients. In recent years, tissue culture has emerged as a valuable technique for genetic preservation and rapid multiplication of cannabis clones. However, there is concern that the physical and chemical conditions of the growing media can induce somaclonal variation, potentially impacting the viability and uniformity of clones. To address this concern, we developed Comparative Restriction Enzyme Analysis of Methylation (CREAM), a novel method to assess DNA methylation patterns and used it to study a population of 78 cannabis clones maintained in tissue culture. Through bioinformatics analysis of the methylome, we successfully detected 2,272 polymorphic methylated regions among the clones. Remarkably, our results demonstrated that DNA methylation patterns were preserved across subcultures within the clonal population, allowing us to distinguish between two subsets of clonal lines used in this study. These findings significantly contribute to our understanding of the epigenetic variability within clonal lines in medicinal cannabis produced through tissue culture techniques. This knowledge is crucial for understanding the effects of tissue culture on DNA methylation and ensuring the consistency and reliability of medicinal cannabis products with therapeutic properties. Additionally, the CREAM method is a fast and affordable technology to get a first glimpse at methylation in a biological system. It offers a valuable tool for studying epigenetic variation in other plant species, thereby facilitating broader applications in plant biotechnology and crop improvement.
RESUMO
Phenotypic diversification is classically associated with genetic differentiation and gene expression variation. However, increasing evidence suggests that DNA methylation is involved in evolutionary processes due to its phenotypic and transcriptional effects. Methylation can increase mutagenesis and could lead to increased genetic divergence between populations experiencing different environmental conditions for many generations, though there has been minimal empirical research on epigenetically induced mutagenesis in diversification and speciation. Whitefish, freshwater members of the salmonid family, are excellent systems to study phenotypic diversification and speciation due to the repeated divergence of benthic-limnetic species pairs serving as natural replicates. Here we investigate whole genome genetic and epigenetic differentiation between sympatric benthic-limnetic species pairs in lake and European whitefish (Coregonus clupeaformis and Coregonus lavaretus) from four lakes (N = 64). We found considerable, albeit variable, genetic and epigenetic differences between species pairs. All SNP types were enriched at CpG sites supporting the mutagenic nature of DNA methylation, though C>T SNPs were most common. We also found an enrichment of overlaps between outlier SNPs with the 5% highest FST between species and differentially methylated loci. This could possibly represent differentially methylated sites that have caused divergent genetic mutations between species, or divergent selection leading to both genetic and epigenetic variation at these sites. Our results support the hypothesis that DNA methylation contributes to phenotypic divergence and mutagenesis during whitefish speciation.
Assuntos
Especiação Genética , Salmonidae , Animais , Salmonidae/genética , Evolução Biológica , Lagos , Epigênese GenéticaRESUMO
The evolutionary histories of adaptive radiations can be marked by dramatic demographic fluctuations. However, the demographic histories of ecologically-linked co-diversifying lineages remain understudied. The Laurentian Great Lakes provide a unique system of two such radiations that are dispersed across depth gradients with a predator-prey relationship. We show that the North American Coregonus species complex ("ciscoes") radiated rapidly prior to the Last Glacial Maximum (80-90 kya), a globally warm period, followed by rapid expansion in population size. Similar patterns of demographic expansion were observed in the predator species, Lake Charr (Salvelinus namaycush), following a brief time lag, which we hypothesize was driven by predator-prey dynamics. Diversification of prey into deep water created ecological opportunities for the predators, facilitating their demographic expansion, which is consistent with an upward adaptive radiation cascade. This study provides a new timeline and environmental context for the origin of the Laurentian Great Lakes fish fauna, and firmly establishes this system as drivers of ecological diversification and rapid speciation through cyclical glaciation.
Assuntos
Lagos , Animais , Great Lakes Region , Peixes/classificação , Peixes/fisiologia , Salmonidae/fisiologia , Salmonidae/genética , Evolução Biológica , Truta/fisiologia , Especiação GenéticaRESUMO
The American eel (Anguilla rostrata) has long been regarded as a panmictic fish and has been confirmed as such in the northern part of its range. In this paper, we tested for the first time whether panmixia extends to the tropical range of the species. To do so, we first assembled a reference genome (975 Mbp, 19 chromosomes) combining long (PacBio and Nanopore and short (Illumina paired-end) reads technologies to support both this study and future research. To test for population structure, we estimated genotype likelihoods from low-coverage whole-genome sequencing of 460 American eels, collected at 21 sampling sites (in seven geographic regions) ranging from Canada to Trinidad and Tobago. We estimated genetic distance between regions, performed ADMIXTURE-like clustering analysis and multivariate analysis, and found no evidence of population structure, thus confirming that panmixia extends to the tropical range of the species. In addition, two genomic regions with putative inversions were observed, both geographically widespread and present at similar frequencies in all regions. We discuss the implications of lack of genetic population structure for the species. Our results are key for the future genomic research in the American eel and the implementation of conservation measures throughout its geographic range. Additionally, our results can be applied to fisheries management and aquaculture of the species.